Cannabis Expectancies for Sleep Modulate Discrepancies Between Subjective and Objective Sleep Outcomes: A Pilot Study

While cannabis use is associated with subjective sleep improvements, studies employing objective sleep measures (e.g. actigraphy) demonstrate mixed relations. Based on social cognitive theory, it is possible that positive sleep-related cannabis expectancies (i.e. beliefs that cannabis will improve sleep) may modify self-reported sleep outcomes. This daily-level study examined agreement between subjective and objective sleep measures and evaluated whether positive sleep-related cannabis expectancies augmented discrepancies between subjective and objective sleep outcomes on cannabis use days. Individuals endorsing regular cannabis use and sleep motives (N = 23) completed baseline measures on cannabis use, sleep, and expectancies, followed by up to seven days of diaries and continuous actigraphy (n = 155 days). Diary and actigraphy agreement was poor for wake after sleep onset and sleep onset latency, moderate for total sleep time, and excellent for fall asleep time and wake-time. Expectancies were associated with overestimated diary total sleep time and this association was amplified on cannabis use days. Tendencies to self-report earlier diary fall asleep time on cannabis use days and later time on nonuse days were amplified as expectancies increased. Sleep-related cannabis expectancies may bias self-reported sleep, highlighting the need to account for such beliefs in future research examining cannabis-sleep relations with subjective measures.